Method of removing an exposed cord on a power transmission belt, an apparatus for carrying out the method, and a power transmission belt made by practicing the method

ABSTRACT

A method of removing a portion of a cord that is exposed on the side surface of a power transmission belt. The method consists of the steps of providing an endless power transmission belt having inside and outside surfaces, laterally oppositely facing side surfaces, and a cord exposed on at least a part of one of the side surfaces. The belt is run in an endless path. The cord that is exposed on the part of the one side surface is ground as the belt is run without grinding the entirety of the one side surface of the belt. The invention is also directed to an apparatus for carrying out the above method and a power transmission belt having a portion of at least one of its side surfaces cut out/ground where a cord was exposed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to power transmission belts of the typehaving longitudinally extending, load carrying cords and, moreparticularly, to a method of removing that portion of the load carryingcords directly exposed at the side surfaces of the belts that areotherwise prone to fraying and/or being separated for the belt duringoperation. The invention is further directed to an apparatus forautomatically removing the exposed cords. The present invention is stillfurther directed to a power transmission belt in which otherwise exposedcords are cut out/ground at the side surfaces of the belt to prevent theaforementioned problem of fraying.

2. Background Art

It is known to sequentially build up belt components on a forming drumto define a belt sleeve, to vulcanize the sleeve, and to divide thevulcanized sleeve into a plurality of individual belts. Such a processis commonly used to form synchronous belts, V-ribbed belts, and V-belts.One component of each of these belts is a load carrying cord, whichdefines the neutral axis for the belt. Typically, the cord is spirallywound over underlying belt components on the drum. Cutting of theindividual belts results in exposure of the load carrying cord at theside surfaces of each belt. The extent of exposure depends upon thetightness of the spiral in which the cord is wrapped. In any event, thecord is generally exposed at less than the entire longitudinal extent ofthe side surfaces of the belt and commonly at 2 or more discretelocations on each side surface of the belt. In those belts in which theside surfaces are not covered by a canvas layer, or the like, theexposed cord repeatedly contacts cooperating pulleys during operation.The frictional forces between the cord and pulley give rise to a raisednap and/or frayed spots. This may result in system vibration duringoperation.

Another problem with those conventional belts having exposed cords isthat the exposed cords are prone to being pulled out of the rubber inwhich they are embedded. This may not only result in significant,unwanted vibration, but may also compromise the integrity of the belt.

It is known to use polyester fiber for load carrying cords. One proposedsolution to the fraying problem associated with polyester fiber cords isdisclosed in U.S. Pat. No. 3,200,662. In this patent, it is taught tofuse the frayed cords by heating the cords to a temperature higher thanthe melting point of the fiber therein.

Aramid fiber has been used to manufacture load carrying cords in powertransmission belts due to its good tensile strength, resistance toelongation and good bending characteristics. Aramid fiber load carryingcords have been used increasingly in synchronous transmission toothedbelts that are run at high speed and severely bent in operation. Thearamid fiber cords are also prone to fraying and/or fluffing uponrepeatedly contacting the cooperating pulleys. While the aramid fibercords have many desirable characteristics that make them suitable foruse in power transmission belts, the binding force of the individualfibers defining the cords is relatively weak, making the cord fibersprone to unwrapping. This phenomenon occurs even in belts in which thearamid fiber load carrying cords are embedded and firmly bonded within arubber layer of the belt. What starts as fraying of the exposed portionof the cords may ultimately result in the individual fibers separatingfrom each other and being pulled out of the belt as the cords repeatedlycontact cooperating pulleys. The withdrawn fibers may wrap around thebelt, the cooperating pulleys and/or the related machinery. This resultsin potential damage to the belt and/or the machine as well as resultingin the inducement of vibration to the operating system if not ultimatefailure of the system.

Various solutions have been proposed to overcome the fraying and fiberseparation problems noted above. Most of these solutions involve theenhancement of the fiber bonding force by treatment of the cords. Forexample, in Japanese Patent Publication No. 31015/1982, a method isdisclosed in which the exposed load carrying cords are solidified withan adhesive.

In Japanese Patent Publication No. 26700/1985, a treatment for aramidfiber cords is disclosed in which the cords are immersed in an aqueoussolution of polyvinyl alcohol, vinyl acetate or gum arabic, or a solventsolution of acrylic ester. The cords are dried after such treatment.

Generally, enhancing the binding force by an adhesive treatment causesthe bending fatigue resistance of the cords to be diminished. Therigidified fibers generally become unsuitable for use in the loadcarrying cords of a power transmission belt. For example, since hardresin is used for the belt, the solidification of the exposed cordportions with ciano, urethane or epoxy adhesive can substantiallyrigidify the cords and the belt. The loss of flexibility is determinedby the degree of penetration of the adhesive. Even if the aramid fibercords are bound firmly with adhesive, after long periods of use, thefibers inside of the belt tend to separate from each other. Frayingoccurs internally with only the external fibers, soaked in the adhesive,remaining adhered to the rubber. However, it has been found that even ifa final twist coefficient is improved and a bonding treatment performedon the cords, the exposed cords eventually develop a raised nap orfrayed portion which not only detracts from the appearance of the beltbut may result in the withdrawal of the fibers from the belt.

One proposed solution to the above problem has been to manually take outthe exposed cords on the side surfaces of the belt, as with a cutter.There are two significant drawbacks with this approach. First of all, itis very time consuming in that it requires the manual manipulation,inspection and cutting of each belt. This becomes very expensive to themanufacturer. Additionally, the procedure may be inconsistentlyperformed on the belts. Localized damage may be inflicted on the belt atthe side surface thereof, which may detract from the belt performance.

A still further known method of overcoming the problems of fraying is toarrange the cords so that there is no exposure thereof at the sidesurfaces of the belt. For example, in Japanese Patent ProvisionalPublication No. 17242/1990, a method of manufacture is disclosed inwhich the ends of the cords are not exposed at the belt side surfaces.The problem with this construction is that the strength of the beltis-diminished by reason of the decrease in the number of cords along thewidth of the belt.

SUMMARY OF THE INVENTION

The present invention is specifically directed to overcoming theabove-enumerated problems in a novel and simple manner.

The invention comprehends a method of removing a portion of a cord thatis exposed on one of the side surfaces of a power transmission belt. Themethod consists of the steps of providing an endless power transmissionbelt having inside and outside surfaces, laterally oppositely facingside surfaces, and a cord exposed on at least a part of one of the sidesurfaces. The belt is run in an endless path. The cord that is exposedon the part of the one side surface is ground as the belt is run,without grinding the entirety of the one side surface of the belt.

By reason of grinding/cutting out the exposed cord, direct contactbetween the cord and cooperating pulley is eliminated. As a result, theproblems of fraying and working loose of the cord fibers are obviatedwithout having to treat the cords as might adversely alter thecharacteristics thereof. At the same time, the appearance of the belt isimproved. Still further, by grinding less than the entirety of the oneside surface of the belt, the integrity of the belt is maintained.

To minimize the removal of material from the side surface of the belt,the invention further contemplates the step of sensing the presence ofthe exposed cord at the one side surface and grinding the one sidesurface and the cord thereat only upon the sensing of the presence ofthe exposed cord.

In one form, a grinding mechanism is provided and is moved selectivelytowards the one side surface, in response to sensing the presence of anexposed cord thereat, and away from the one side surface in the absenceof sensing the presence of an exposed cord thereat.

To operate the belt in the endless path, in a preferred form, the beltis trained around first and second spaced pulleys. At least one of thepulleys is driven to effect running of the belt.

To facilitate accurate cutting of only the exposed part of the cord, therunning belt is stabilized at a location between the first and secondpulleys and preferably at the location where the grinding is performed.In one form, opposing rollers are provided to act against the inside andoutside surfaces of a belt to thereby effect stabilization.

To further control the positioning of the belt relative to the grindingmechanism, the first and second pulleys can have flanges thereon with aspacing substantially equal to the width of the belt. This preventsshifting of the belt laterally thereof relative to the grindingmechanism. Further stability is afforded by repositioning the first andsecond pulleys to thereby tension the unsupported portion of the beltbetween the first and second pulleys so as to further facilitategrinding.

To improve the efficiency of the grinding operation, in one form,separate grinding mechanisms are provided to simultaneously act on theopposite side surfaces of the belt. Each is associated with a separatesensor to be movable independently towards and away from its respectivebelt side surface.

In one form, the grinding mechanism(s) includes a rotary grinding wheelto act against the side surface of the belt. In a preferred form, thegrinding wheel has a rotary axis that is substantially parallel to theaxes of the first and second pulleys. The dimension of the grindingwheel taken along its axis is not substantially greater than thediameter of the cord exposed at the belt side surface. This makespossible the removal of the cord without significant removal of therubber layer in which the cord is embedded so as not to compromise thebelt's performance.

In a preferred form, the belt is run in a first direction and thegrinding wheels operated so as to engage the belt and move against thebelt in a direction opposite to the first direction. The invention alsocomprehends rotation of the grinding wheels in the same direction as thebelt is advanced. A sensing mechanism is provided to produce a signal inresponse to sensing the presence of an exposed cord. The grindingmechanism(s) is activated/deactivated as an incident of the signalgeneration by the sensor, upon its detecting the presence/absence of anexposed cord.

The inventive method has utility for all types of belts, to includesynchronous belts, V-belts and V-ribbed belts.

The invention further contemplates an apparatus for removing a portionof a cord that is exposed on a side surface of a power transmission beltand having a belt supporting structure on which an endless powertransmission belt can be trained and run in an endless path, a sensor todetect the presence of a cord exposed on the side surface of a beltrunning on the belt supporting structure, a grinder for the sidesurfaces of the belt, and a mechanism for selectively activating anddeactivating the grinder in response to sensing the presence and absenceof an exposed cord.

Preferably, the grinder has a rotatable grinding wheel which isactivated by being moved against the side surface of a running belt anddeactivated by being moved away from the belt side surface.

Preferably, the belt supporting structure has spaced pulleys about whichthe belt is trained, with the pulleys being movable selectively towardsand away from each other to alter the tension on the belt. A greatertension on the belt results in greater stability of the belt between thepulleys, at which location the side surfaces are preferably ground.

To further stabilize the running belt, first and second cooperatingrollers are provided to act on the inside and outside surfaces of thebelt. This prevents shifting of the belt and allows precision grindingof only that portion of the belt side surface at which the cord isexposed. The stabilizing structure preferably includes first and secondcooperating rollers defining a space therebetween for reception of abelt running on the belt supporting structure.

The invention further contemplates the combination of the aboveapparatus and an endless power transmission belt having load carryingcords extending lengthwise of the belt, inside and outside surfaces, andlaterally spaced side surfaces.

In a preferred form, the load carrying cords are made from aramid fiber.

In one form, the apparatus has a frame with a supporting plate that ismounted to the frame for movement in two transverse directions relativeto the frame. The grinder is preferably mounted on a supporting plate tofollow movement thereof.

In one form, one of the rollers in the stabilizing roller pair is fixedwhile the other is movable selectively towards and away from the fixedroller.

The invention further contemplates a power transmission belt having abody with a tension/outer section and a compression/inner section anddefining laterally oppositely facing side surfaces. A load carrying corddefines a neutral axis for the belt. At least a portion of the loadcarrying cord is cut to define a recess at at least one of the sidesurfaces of the belt to thereby prevent direct contact between the loadcarrying cord at the recess and a pulley with which the belt cooperates.

The load carrying cord, in one form, is made from aramid fiber.

The belt has a longitudinal extent. In a preferred form, the recess doesnot extend continuously along the length of the one side surface and isnot significantly deeper, in a lateral direction, than the diameter ofthe cord.

In one form, the belt has a plurality of teeth with a constant pitchspaced longitudinally of the belt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an apparatus, according to the presentinvention, for removing a portion of a cord that is exposed on the sidesurface of a power transmission belt;

FIG. 2 is a side elevation view of the apparatus in FIG. 1;

FIG. 3 is an enlarged, fragmentary, side elevation view of cord sensingand grinding mechanisms in relation to a power transmission belt on theapparatus in FIGS. 1 and 2;

FIG. 4 is an enlarged, fragmentary, plan view of stabilizing rollers anda grinding mechanism shown in relationship to a belt on the inventiveapparatus;

FIG. 5 is a fragmentary perspective view of a synchronous powertransmission belt with a load carrying cord therein exposed at a recessformed in a side surface of the belt;

FIG. 6 is a view as in FIG. 5 with the exposed portion of the cordcompletely removed at the side surface of the belt so as to leave anempty recess.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIGS. 1 and 2, an apparatus, according to the present invention, isshown at 10 for removing a portion of a cord that is exposed on the sidesurface of a power transmission belt. The apparatus 10 has a frame 12upon which the various components of the apparatus 10 are supported.

The apparatus 10 has a belt running section 14, having first and secondspaced pulleys 16, 18 rotatable about spaced, parallel axes 20, 22,respectively. An endless, power transmission belt 24 is trained aroundthe pulleys 16, 18 so as to permit running thereof in an endless patharound the pulleys 16, 18. The pulleys 16, 18 have axially spacedflanges 26, 28, (one shown on each pulley 16, 18). The flanges 26, 28define a groove on each pulley 16, 18 approximately equal to the width W(FIG. 2) of the power transmission belt 24 to be operated on by theapparatus 10. The flanged pulleys 16, 18 prevent vertical shifting ofthe power transmission belt 24 relative to the pulleys 16, 18 to therebyfacilitate precision grinding of the power transmission belt 24, asdescribed below.

Further stability is provided for the running belt 24 by a stabilizingroller pair 30 provided at an unsupported belt portion midway betweenthe pulleys 16, 18. The roller pair 30 consists of a fixed roller 32,which is rotatable about a fixed axis 34 that is generally parallel tothe axes 20, 22 of the pulleys 16, 18, and a press roller 36, that isrotatable about an axis 38 that is substantially parallel to the axis 34of the roller 32. As described in greater detail below, the press roller36 is movable in a direction perpendicular to its axis selectivelytowards and away from the roller 32 to selectively diminish and enlargethe space between the rollers 32, 36. The rollers 32, 36 are arranged sothat the fixed roller 32 acts against an inside surface 40 on therunning belt 24, with the press roller 36 acting against an outsidesurface 42 of the belt 24. The opposing surfaces on the rollers 32, 36cooperatively prevent shifting of the belt in an inside-outside linei.e. in a direction perpendicular to the plane containing the pulleyaxes 20 22.

The grinding mechanisms 44 are provided, one each at the opposite sidesurfaces 46, 48 of the belt 24, in the vicinity of the stabilizingroller pair 30. Each grinding mechanism 44 has a grinding wheel 50 thatis rotatable about an axis 52 that is substantially perpendicular to theaxes 20, 22 of the pulleys 16, 18. As seen most clearly in FIG. 4, eachgrinding wheel 50 has a thickness T that is not substantially largerthan the diameter of a load carrying cord 54 in the belt 24. Thegrinding wheel 50 is designed to remove primarily the portion of thecord 54 that is exposed at the belt side surfaces 46, 48, withoutremoving additional portions of the belt that might compromise theintegrity thereof.

The grinding mechanisms 44 are carried one each on vertically spacedsupporting plates 56, with one such plate 56 being provided above thebelt in FIG. 2 and one such plate 56 being provided below the belt 24 inFIG. 2. Through a motor 58, the plates 56 are vertically movable towardsand away from each other to selectively activate and deactivate thegrinding mechanisms 44. This movement is dictated by sensors 60,provided one each at the separate side surfaces 46, 48 of the belt 24.The sensors 60 are constructed to sense the presence of an exposed loadcarrying cord 54 at the side surfaces 46, 48 of the belt 24 and toproduce a signal to a controller 62 which directs operation of the motor58 to independently move the grinding wheels 50 towards and away fromthe belt side surfaces 46, 48. As a result, the belt side surfaces 46,48 can be ground at only those locations where the load carrying cord 54is exposed. The details of the above described system will now bedescribed.

To effect driving of the belt 24 at the belt running section 14, a primemover 64 is provided and includes a drive pulley 66 which rotates thepulley 18 through a power transmission belt 68 trained around the pulley66 and a pulley 70 fixed to the shaft 72 carrying the pulley 18.

The driven pulley 16 is movable selectively towards and away from thedrive pulley 18 by a tensioning mechanism 74. The tensioning mechanism74 has an operating cylinder 76 fixed to the frame 12. The operatingcylinder 76 selectively extends and retracts a shaft 78. The free end 80of the shaft 78 is connected to the pulley 16 so that extension andretraction of the shaft 78 effects reciprocating movement of the pulley16 in the line of double-headed arrow 82, selectively towards and awayfrom the pulley 18.

By directly the pulley 16 towards the pulley 18, mounting of the belt 24on the pulleys 16, 18 is facilitated, as is the removal of the belt 24after completion of the grinding operation. The tensioning mechanism 74allows a desired tension to be placed on the running belt 24 to cause itto consistently run in a straight line.

The belt 24 which operates on the running section 14 may take a varietyof different forms. For example, the belt 24 can be a synchronous belt,a V-belt, a V-ribbed belt, etc. The invention is designed mainly tooperate on belts having a cut edge; that is belts that have exposed sidesurfaces 46, 48 that are uncovered by any layer such as canvas fabric.

An exemplary synchronous belt 24 is shown in detail in FIGS. 5 and 6.The belt 24 has a body 84 defining a outer section 86 and inner section88. The inner section 88 has a plurality of teeth 90 spaced at regularintervals lengthwise of the belt 24. In a V-belt or V-ribbed belt, thecorresponding outer section 86 would be a tension section and thecorresponding inner section 88 would be a compression section. Laterallyspaced, load carrying cords 54 define the neutral axis for the belts 24.

It is known to construct a belt such as the belt 24 in FIGS. 5 and 6 bysequentially building components up on a forming drum to provide a beltsleeve from which a plurality of belts are ultimately cut. The loadcarrying cord component 54 is applied by wrapping a cord around theforming drum (not shown) in a spiral pattern. Upon completion of thesleeve formation, the sleeve is normally vulcanized and thereafter theindividual belts 24 are cut from the sleeve. This cutting step exposesthe cords 54 at only spaced locations spaces along the length of thebelt side surfaces 46, 48, as shown in FIG. 5.

The present invention is directed to grinding out primarily the exposedportion of the cords 54 at the belt side surfaces 46, 48. It is anobject of the invention to completely remove the exposed cords 54 sothat they are not prone to fraying or dislodging during use whileminimizing the removal of other portions of the belt. Consequently,precision is a significant objective of the present invention, and it istherefore important to consistently run and effectively stabilize thebelt 24 during a grinding operation.

While the tensioning of the belt 24, through the mechanism 74, affords acertain amount of stability for the belt 24, the primary stabilizingfunction is accomplished by the roller pair 30. The fixed roller 32preferably has axially spaced flanges 92 (one shown) to define a grooveto closely accept the width of the belt 24. Thus the roller 32 maintainsthe belt 24 at a constant height between the pulleys 16, 18.Accordingly, the belt 24 at all times travels in a substantially linearpath so that it is not bent or twisted as might alter its alignment withthe grinding mechanisms 44. To prevent the running belt 24 fromfluttering, the press roller 36 is biased by a spring mechanism, shownschematically at 94, against the outside belt surface 42 to therebypress the belt 24 into the groove defined by the roller 32. The rollerpair 30 thus holds the belt 24 in a precise location midway between thepulleys 16, 18 to be operated on by the grinding mechanisms 44.

The grinding mechanisms 44 are substantially the same both above andbelow the running belt 24. Accordingly, only the representative grindingmechanism 44 located above the running belt 24 will be described. Thegrinding wheel 50 is journalled for rotation in a housing 96 carried onthe supporting plate 56. The shaft 98 carrying the wheel 50 projectsthrough the housing 96 to be driven by a motor 100, carried on thesupporting plate 56, through a power transmission belt 102. The plate 56is operatively connected to a shaft 104 that is selectively extended andretracted by the motor 58 to thereby lower and raise the supportingplate 56. Raising of the upper supporting plate 56 deactivates thegrinding mechanism 44 by moving the grinding wheel 50 on the grindingmechanism 44 away from the side surface of the belt 24. The grindingmechanisms 44 are arranged so that the rotational axes of the grindingwheels 50 thereon are in vertical coincidence.

The invention also contemplates that the grinding wheels 50 beadjustable along their rotational axes i.e. between the inside surface40 and outside surface 42 of the running belt 24. To facilitate this,four vertically extending, parallel guide rods 106, 108, 110, 112 areprovided. The rods 106, 108, 110, 112 project through each of thesupporting plates 56 and guide vertical movement thereof. The lowerportions of the rods 106, 108, 110, 112 are fixed to a base plate 114.The base plate 114 has associated guide blocks 116, 118 to cooperatewith guide rails 120, 122 on a surface 124 which supports the apparatus10. The base plate 114 is movable lengthwise relative to the rails 120,122 by a drive motor 126, which selectively extends and retracts a shaft128 attached to the base plate 114. This alters the position of thegrinding wheels 50 between the inside surface 40 and outside surface 42of the belt 24.

The grinding wheels 50, in a preferred form, have a grinding surfaceelectro-deposited with diamond having a grain size between No. 80 andNo. 120. Alternatively, grindstones having a high hardness WA grindingmaterial may be utilized. The cutting edge may have a rounded surface toengage the belt 24 so as to produce a U-shaped cut in the belt inconformity with the contour of the cord 54. Alternatively, the grindingsurface can be flat. Slits may be provided at spaced intervals aroundthe periphery of the cutting surface of the wheel 50. Preferably, thewidth of the grinding wheels 50 i.e. their axial extent, is between 0.4and 1.0 mm.

The grinding wheels 50, as previously noted, are activated anddeactivated in response to a signal from the sensors 60. The sensors 60are preferably photoelectric switches that detect the presence of anexposed cord 54. More particularly, the sensors are chosen to detect thecolor of the load carrying cord's being different than the color of therubber in which the load carrying cords 54 are embedded. Generally, thecord 54 is exposed in two to three places around the length of the belt24 at each side surface 46, 48. This location varies on the oppositeside surfaces 46, 48 for the belt which makes desirable the independentoperation of the grinding mechanisms 44. In the absence of thisindependent operation, it is possible that one of the grindingmechanisms 44 might dig up exposed cord that is otherwise fullyembedded, thereby giving rise to the problem of fraying and dislodgingof the cord fibers. Further, the belt 24 could be otherwise weakened byreason of the grinding out of the material other than the cord 54.

Accordingly, it is an important feature of the present invention toidentify the presence of the cord 54 that is exposed at the sidesurfaces 46, 48 and to grind only the exposed cord portions out of thebelt 24. To accomplish this, the sensors 60 are situated upstream of thegrinding mechanisms 44. Once a sensor 60 detects the presence of anexposed cord 54, the sensor 60 causes the signal receiving controller 62to operate the associated motor 100 to activate the grinding mechanism44. Once the entire extent of the exposed cord 54 is ground out, themotor 58 retracts/deactivates the grinding mechanism 44. The pressroller 36 is mounted on a bracket 130 fixed to the end of a rod 132. Therod 132 is slidable guidingly over the rods 106, 108, 110, 112 and ismovable with the supporting plates 56 lengthwise of the rails 120, 122.The force of the spring 94 determines in part the amount of pressureapplied by the press roller 36 against the belt 24.

Detailed operation of the apparatus 10 will be described below.Initially, the tensioning mechanism 74 is operated to advance the drivenpulley 16 towards the drive pulley 18. A belt 24 is then trained aroundthe pulleys 16, 18. Thereafter, the tensioning mechanism 74 is operatedto move the pulley 16 away from the pulley 18 to thereby exert a tensionon the mounted belts 24. The belt tension is preferably in the range of40 to 100 kg. At the same time, the fixed roller 32 is engaged with theinside surface 40 of the belt 24.

The prime mover 64 and grinding motors 100 are then activated. The primemover 64 is set to rotate the belt 24 with a peripheral velocity of 5 to20 mm per second. The drive motor 126 is then operated to reposition thebase plate 114 so as to situate the cutting surfaces of the grindingwheels 50 at the location of the cords 54 in the belt 24. This movementof the base plate 114 also situates the press roller 36 against theoutside surface 42 of the belt 24. Preferably, the pressure exerted bythe press roller 36 on the belt 24 is between 15 to 30 kg.

The activated sensors 60, upon detecting the presence of an exposedportion of the load carrying cord 54 at the belt side surfaces 46, 48,activate the motor 58 on that side of the belt 24 on which the exposedcord 54 is detected to advance a grinding mechanism 44 on that sidetowards the belt 24 to bring the grinding wheel 50 into engagement withthe exposed cord 54 on the belt side surface 46, 48. The grinding wheels50 are rotated in the direction of arrows 134,136, as shown in FIGS. 2and 3, which direction is opposite to the direction of advancement ofthe belt, as shown by arrow 138 in those same figures. The inventionalso comprehends rotation of the wheels 50 in the same direction as thebelt 24 advances. The abutting pressure of the grinding wheel 50preferably does not exceed 20 kg. A preferred range of pressure isbetween 5 and 10 kg.

The wheels 50 positively grind the load carrying cord 54 at the beltside surface 46, 48. Positive grinding results in the complete diggingout of the cord 54 without wrapping of the cord fibers around thegrinding wheel 50.

A timer mechanism, shown schematically at 140 in FIG. 2, determines whenthe entire length of the belt 24 has been operated on by the apparatus10. Once this occurs, the grinding wheels 50 are retracted and the primemover 64 is stopped to halt the running of the belt 24. The tensioningmechanism 74 is then operated to advance the pulley 16 towards thepulley 18 to relax the tension on the belt 24. At the same time, thedrive motor 126 is operated to move the grinding wheels 50 downwardlyaway from the belt 24. All of the above mentioned steps occur in anautomatic sequence. Thereafter, the completed belt 24 can be removedfrom the apparatus 10.

The invention is also directed to a belt 24 to be produced by practicingthe inventive method. While the inventive method can be practiced usingany type of power transmission belt with an exposed side surface, thedetails of an exemplary synchronous belt, as shown in FIGS. 5 and 6herein, will be described in detail.

The belt 24 in FIGS. 5 and 6 has cords 54 made from aramid fiber. Thesynchronous belt 24 shown typically has the load carrying cords 54accurately positioned on the pitch line for the belt 24 so that precisegrinding of only the exposed portions of the cords 54 can be carriedout.

In FIG. 6, the side surface 48 of the belt 24 has been ground outaccording to the invention to thereby leave a recess 142 in the beltside surface 48. As can be seen, the cross section of the recess 142 isU-shaped resulting from the use of a grinding wheel 50 with a curvedcutting surface. The recess 142 in FIG. 6 is formed so as to completelyremove the exposed cord 54. In FIG. 5, the cord exposed at the belt sidesurface 84 is only partially ground so as to reside entirely within therecess. That is, it is spaced laterally inwardly from the belt sidesurface 48.

In a preferred form, the rubber in the outer section 86 and innersection 88 is a rubber with good heat resistance, such as chloroprenerubber (CR), chlorosulfonated polyethylene rubber (CSM), alkylatedchlorosulfonated polyethylene rubber (ACSM), or acrylonitrilehydride-butadiene rubber (also identified as hydrogenated nitrile rubberidentified by H-NBR), obtained by adding at least 80 weight percent ofhydrogen to the double bonded portion of acrylonitrile-butadiene rubber.

A cover canvas 144 is provided on the inside surface 40 of the belt 24over the teeth 90. The cover canvas 144 may be plain weave, twill orsatin fabric stretchable in the direction of the warp i.e. thelongitudinal direction of the belt. The canvas fabric has warp and weftyarns that alternatingly cross over and under each other at everyintersection of the warp and weft yarns. On the other hand, twill orsatin fabric normally have crossing warp and weft yarns which alternateover and under at less than every intersection. The result of this isthat the rubber with which the canvas 144 is commonly impregnated,permeates not only the areas bounded by the yarn but the space betweenthe warp and weft yarns at points of intersection. The rubber betweenthe yarns at the intersection points prevents direct contact between thewarp and weft yarns, as when the belt is bent. This contributes to thelongevity of the belt. Because of this feature, twill and satin fabricsare preferred for the cover canvas 144.

The cords 54 are preferably made up of 100 to 3000 filaments, each of 1to 3 denier, which are twisted into a raw cord of 300 to 3100 denier.The filaments of the raw cord are bonded together by adhesive treatmentin a liquid that is preferably one of epoxy or isocyanate compounds.This treatment increases the binding force of the filament, to reducethe possibility of fraying. The twisted filaments are then subjected toan RFL treatment, followed by an overcoating with rubber paste.Alternatively, the cord 54 can be directly overcoated with a rubberpaste. The bonding treatment utilizing the rubber paste can be repeated,if necessary.

The aramid fiber in the cords 54 contains aromatic rings in the majorchains of the molecular structure. Products suitable for constructingthe load carrying cords 54 are commercially available and sold under thefollowing trademarks: KONEX™, NOMEX™, KEVLAR™, TECHNOR™ and TWARON™.

The foregoing disclosure of specific embodiments is intended to beillustrative of the broad concepts comprehended by the invention.

We claim:
 1. In combination:a) an endless power transmission belt having a length, inside and outside surfaces, and laterally spaced side surfaces, said belt further having a body with a cord embedded therein; and b) an apparatus for removing a portion of the cord that is exposed on a surface of the power transmission belt, said apparatus comprising: a supporting structure on which the endless power transmission belt is trained and run in an endless path; means for sensing the presence of the cord exposed on the surface of the belt running on the belt supporting structure and for producing a signal indicative of the presence of the cord exposed on the surface of the belt; means for grinding the surface of the belt running on the belt supporting structure; and means for selectively a) activating the grinding means in response to the signal from the sensing means sensing the presence of the cord exposed on the side surface of the belt running on the belt supporting structure and b) deactivating the grinding means in response to the sensing means not sensing the presence of the cord exposed on the surface of the belt running on the belt supporting structure and not producing the signal indicative of the presence of the cord exposed on the surface of the belt, whereby the grinding means can be controlled to grind the belt surface only where an exposed portion of the cord is sensed by the sensing means.
 2. The combination according to claim 1 wherein the grinding means includes a grinding wheel rotatable about an axis.
 3. The combination according to claim 2 wherein the belt supporting structure comprises first and second spaced pulleys each rotatable about an axis and the axes of the first and second pulleys are substantially perpendicular to the axis of the grinding wheel.
 4. The combination according to claim 1 wherein the belt supporting structure comprises first and second spaced pulleys and including means for stabilizing the belt running on the belt supporting structure between the first and second pulleys.
 5. The combination according to claim 4 wherein the stabilizing means comprises first and second cooperating rollers with a space therebetween for reception of the belt running on the belt supporting structure.
 6. The combination according to claim 3 wherein the means for activating and deactivating comprises means for moving the grinding wheel selectively towards and away from the belt on the belt supporting structure.
 7. The combination according to claim 1 including means adjacent to the grinding means for stabilizing the belt running on the belt supporting structure.
 8. The combination according to claim 7 wherein the stabilizing means comprises first and second cooperating rollers between which the belt running on the belt supporting structure operates.
 9. The combination according to claim 3 including means for urging one of the first and second pulleys away from the other of the first and second pulleys with a variable force to alter the tension on the belt running on the belt supporting structure.
 10. The combination according to claim 2 wherein said grinding wheel has an axial dimension that is less than the distance between the inside and outside belt surfaces.
 11. The combination according to claim 10 wherein the load carrying cords have a diameter and the axial dimension of the grinding wheel is not substantially larger than the diameter of the load carrying cords.
 12. The combination according to claim 10 wherein the load carrying cords are made from aramid fiber.
 13. The combination according to claim 12 wherein the power transmission belt is one of a V-belt, V-ribbed belt, and synchronous belt.
 14. In combinationa) an endless power transmission belt having a length, inside and outside surfaces, and laterally spaced side surfaces, said belt further having a body with a cord embedded therein; and b) an apparatus for removing a portion of the cord that is exposed on the side surface of the power transmission belt, said apparatus comprising: a belt supporting structure on which the power transmission belt is trained and run in an endless path; means for grinding at least one side surface of the belt running on the belt supporting structure; means for sensing the presence of the cord exposed at the one side surface, said grinding means including a grinding wheel to grind the one side surface; and means for activating the grinding means in response to a signal from the sensing means upon the sensing means detecting the presence of the cord exposed at the one side surface, whereby the grinding means, sensing means, and activating means can be operated to sense and grind a cord exposed at the one side surface as the belt is continuously run on the belt supporting structure.
 15. The combination according to claim 14 wherein the load carrying cord has a first diameter between the inside belt surface and the outside belt surface, the grinding wheel being dimensioned to engage the belt running on the belt supporting structure along a line between the inside and outside surfaces of the belt that is approximately equal to the first diameter.
 16. The combination according to claim 14 including a frame, a supporting plate, means for mounting the supporting plate to the frame for movement in two transverse directions relative to the frame and means for mounting the grinding means on the supporting plate to follow movement of the supporting plate.
 17. The combination according to claim 16 wherein the grinding means comprises a housing in which the grinding wheel is journalled for rotation and means for rotating the grinding wheel in the housing.
 18. The apparation according to claim 14 wherein the belt supporting structure includes first and second flanged pulleys about which a belt can be trained.
 19. The apparation according to claim 18 including belt stabilizing means comprising cooperating first and second rollers for capturing a belt on the belt supporting structure between the first and second pulleys, a frame, means for mounting one of the first and second rollers to the frame for rotation about a first fixed axis, and means for mounting the other of the first and second rollers to the frame for rotation about a second axis that is parallel to the first axis and for movement selectively towards and away from the one of the first and second rollers.
 20. The combination according to claim 18 wherein the belt has a predetermined width and said first and second flanged pulleys each have a flange pair spaced to closely accept the width of the belt.
 21. In combination:a) an endless power transmission belt having a length, inside and outside surfaces, and laterally spaced side surfaces, said belt further having a body with a cord embedded therein; and b) an apparatus for removing a portion of the cord that is exposed on a side surface of the power transmission belt, said apparatus comprising: a frame; a belt supporting structure on the frame including spaced first and second pulleys on which the endless power transmission belt is trained and run in an endless path; means on the frame for stabilizing the belt including first and second rollers between which the belt on said belt supporting structure passes; grinding means including first and second grinding wheels; and means for mounting the grinding wheels to the frame for movement one each towards and away from a side surface on the belt trained around the first and second pulleys to remove an exposed cord portion on the side surfaces of the belt trained around the first and second pulleys. 